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首页> 外文期刊>International Journal of Heat and Mass Transfer >Near-field radiative heat transfer between rough surfaces modeled using effective media with gradient distribution of dielectric function
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Near-field radiative heat transfer between rough surfaces modeled using effective media with gradient distribution of dielectric function

机译：使用具有介电函数梯度分布的有效介质对粗糙表面之间的近场辐射传热进行建模

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Near-field radiative heat transfer (NFRHT) between rough surfaces, due to its widespread presence in engineering practice of near-field energy utilization, requires indepth studies, especially from the perspective of physical mechanism. In this paper, an effective multilayer model is built to approach the NFRHT between random rough surfaces of silicon carbide (SiC). Using the effective medium theory (EMT), the effective dielectric function of each layer is obtained, which forms a gradient distribution of dielectric function along the depth of the medium. The influence of the effective dielectric function on surface phonon polaritons (SPhPs) is analyzed, showing that the effective layers with small filling fraction of SiC feature lower SPhP resonance frequencies than SiC bulk. The coupling of SPhPs from the gradient distribution of dielectric function produces new surface modes that dominates the NFRHT. Investigation on the effect of root mean square height (RMS height, sigma) reveals that the peaks of local density of states (LDOS) and spectral heat flux are red-shifted as sigma increases, while the spectral heat flux below the peak frequency gets larger. This can be attributed to the coupling of SPhPs inside the rough layer. We also found the total net heat flux between rough surfaces separated by an average distance exceeds that between smooth plates and increases with increasing sigma, which offer a new way to enhance NFRHT. This work provides a reference for the simulation and understanding of the NFRHT between rough surfaces. (C) 2019 Elsevier Ltd. All rights reserved.
机译：由于粗糙表面之间的近场辐射热传递（NFRHT）在近场能量利用的工程实践中广泛存在，因此需要进行深入研究，尤其是从物理机制的角度进行研究。在本文中，建立了一种有效的多层模型来逼近碳化硅（SiC）随机粗糙表面之间的NFRHT。使用有效介质理论（EMT），可以获得每一层的有效介电函数，它沿着介质的深度形成了介电函数的梯度分布。分析了有效介电功能对表面声子极化子（SPhPs）的影响，表明SiC填充率较小的有效层的SPhP共振频率低于SiC体。 SPhPs与介电函数梯度分布的耦合产生了主导NFRHT的新表面模式。对均方根高度（RMS高度，sigma）的影响的研究表明，随着sigma的增加，局部状态密度（LDOS）和光谱热通量的峰值发生红移，而低于峰值频率的光谱热通量变大。这可以归因于粗糙层内部SPhP的耦合。我们还发现，以平均距离分隔的粗糙表面之间的总净热通量超过了光滑板之间的总热通量，并且随着sigma的增加而增加，这提供了一种增强NFRHT的新方法。这项工作为模拟和理解粗糙表面之间的NFRHT提供了参考。 （C）2019 Elsevier Ltd.保留所有权利。

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